Enhancing mineral nutrient availability and corn productivity with biostimulants

Corn (Zea mays L.) production has greatly increased since corn was first domesticated some 7,000 years ago (Beadle, 1980). Generating improved cultivars with novel breeding schemes and genetics in combination with enhanced management factors and technologies has resulted in the highest corn grain yields to date. Some of the most important management factors that have been utilized are hybrid, planting population, nitrogen fertility, additional nutrient fertility, and foliar protection (Ruffo et al., 2015). In recent years, a new technology has been discussed, namely, biological products. These products have a wide variety of uses but are typically intended to increase crop growth, relieve crop stresses, enhance the availability of soil mineral nutrients, improve the accumulation of mineral nutrients, and ultimately increase yields. In an effort to better understand biological products and their best fit in an agronomic management system, the objective of this research was to evaluate the effects of two biological products regarding their optimal application to provide increased soil nutrient availability and enhanced fertilizer use in corn production. This research involved the following two areas: Utilizing a Microbial Enhancer to Improve Nitrogen Use and Corn Productivity Multiple application methods and timings of a microbial enhancer were applied in combination with differing rates of nitrogen (N) fertilizer to evaluate the responses in N availability and use by corn. Certain application methods resulted in improvements in N uptake and use efficiency corresponding with grain yield increases. When applied earlier in the growing season, the yield trajectory was enhanced, evidenced by more kernel production, while later application timings resulted in heavier kernels. Improving Fertilizer Use and Corn Productivity with a Phosphorus Solubilizing Bacteria Differing rates of N and phosphorus (P) fertilizer were used in combination with applications of a phosphorus solubilizing bacteria (PSB) to determine the effects of a PSB on accumulation of essential nutrients by corn plants. Phosphorus solubilizing bacteria applications enhanced the amount of available phosphorus in the soil, thereby increasing the amount of phosphorus accumulated in the plants. This enhancement in available P corresponded with increases in grain yield due to a higher production of kernels

Jahn-Teller Distortions, Cation Ordering and Octahedral Tilting in Perovskites

In transition metal oxides, preferential occupation of specific d orbitals on the transition metal ion can lead to the development of a long-range ordered pattern of occupied orbitals. This phenomenon, referred to as orbital ordering, is usually observed indirectly from the cooperative Jahn-Teller distortions (CJTDs) that result as a consequence of the orbital ordering. This paper examines the interplay between orbital ordering, octahedral tilting and cation ordering in perovskites. Both ternary AMX3 perovskites containing an active Jahn-Teller (J-T) ion on the octahedral site and quaternary A2MM\u27X6 perovskites containing a J-T ion on one-half of the octahedral sites have been examined. In AMX3 perovskites, the tendency is for the occupied 3d3x2-r2 and 3d3z2-r2 orbitals to order in the ac plane, as exemplified by the crystal structures of LaMnO3 and KCuF3. This arrangement maintains a favorable coordination environment for the anion sites. In AMX3 perovskites, octahedral tilting tends to enhance the magnitude of the J-T distortions. In A2MM\u27X6 perovskites, the tendency is for the occupied 3d3z2-r2 orbitals to align parallel to the c axis. This pattern maintains a favorable coordination environment about the symmetric M\u27-cation site. The orbital ordering found in rock-salt ordered A2MM\u27X6 perovskites is compatible with octahedral rotations about the c axis (Glazer tilt system a0a0c-) but appears to be incompatible with GdFeO3-type octahedral tilting (tilt system a-b+a-)

Prediction of the Crystal Structures of Perovskites Using the Software Program SPuDS

The software program SPuDS has been developed to predict the crystal structures of perovskites, including those distorted by tilting of the octahedra. The user inputs the composition and SPuDS calculates the optimal structure in ten different Glazer tilt systems. This is performed by distorting the structure to minimize the global instability index, while maintaining rigid octahedra. The location of the A-site cation is chosen so as to maximize the symmetry of its coordination environment. In its current form SPuDS can handle up to four different A-site cations in the same structure, but only one octahedral ion. Structures predicted by SPuDS are compared with a number of previously determined structures to illustrate the accuracy of this approach. SPuDS is also used to examine the prospects for synthesizing new compounds in tilt systems with multiple A-site coordination geometries (a+a+a+, a0b+b+, a0b-c+)

Magnetic structures of NaLMnWO_6 perovskites (L=La,Nd,Tb)

The magnetic structures of the perovskites NaLaMnWO_6, NaNdMnWO_6, and NaTbMnWO_6, with rocksalt ordering of the Mn/W ions and layered ordering of Na and the rare-earth ions, have been determined by neutron powder diffraction. The manganese moments in NaLaMnWO_6 order below 10 K with a propagation vector of k_14=(1/2,0,1/2) and a moment of 3.99μB per Mn^2+ ion. The Mn^2+ and Nd^3+ ions order simultaneously in NaNdMnWO_6 at 11 K. The resulting magnetic structure is incommensurate with the underlying crystal structure and has the propagation vector of k_5=(0,0.48,1/2). NaTbMnWO_6 undergoes two magnetic phase transitions at 15 and 9 K. The structure determined at 11 K is based on two propagation vectors of k_14=(1/2,0,1/2) and k_5=(0,0.427,1/2). Upon cooling at 6 K the incommensurate vector is no longer present and the moments order only according to k_14. The moments of the Nd and Tb ions are found to remain within the planes of the A-site cations, and in NaTbMnWO_6 the Mn moments also lie within the xy plane. This study not only reveals magnetic structures with previously unexplored topologies but it also sheds light on the intricate coupling between the two magnetic sublattices

MetaPOAP: Presence or Absence of Metabolic Pathways in Metagenome-Assembled Genomes

Genome-resolved metagenomics allows the construction of draft microbial genomes from short-read shotgun metagenomics (Metagenome-Assembled Genomes, or MAGs); however, even high-quality MAGs are typically somewhat incomplete and contain a small amount of contaminant sequence, making accurate prediction of metabolic potential challenging. Here, we describe MetaPOAP, an algorithm for probabalistic assessment of the statistical likelihoods for the presence or absence of metabolic pathways in MAGs